1. Field of the Invention
The present invention relates to video processing technology. In one aspect, the present invention relates to the display of digital video information in multiple rotated formats.
2. Description of the Related Art
Because video information requires a large amount of storage space, video information is generally compressed. Accordingly, to display compressed video information which is stored, for example on a CD-ROM or DVD, the compressed video information must be decompressed to provide decompressed video information. The decompressed video information is then provided in a bit stream to a display. The decompressed bit stream of video information is typically stored as a bit map in memory locations corresponding to pixel locations on a display. The video information required to present a single screen of information on a display is called a frame. A goal of many video systems is to quickly and efficiently decode compressed video information so as to provide motion video by displaying a sequence of frames.
Standardization of recording media, devices and various aspects of data handling, such as video compression, is highly desirable for continued growth of this technology and its applications. A number of (de)compression standards have been developed or are under development for compressing and decompressing video information, such as the Moving Pictures Expert Group (MPEG) standards for video encoding and decoding (e.g., MPEG-1, MPEG-2, MPEG-3, MPEG-4, MPEG-7, MPEG-21) or the Windows Media Video compression standards (e.g., WMV9). Each of the MPEG and WMV standards are hereby incorporated by reference in its entirety as if fully set forth herein.
In recent years, there has been a significant increase in the number of portable devices that are used to display video data using one of the standards discussed hereinabove. Many applications for the display of visual images require the ability to rotate the image. Prior art systems for rotating video images require that an entire frame of the video image be stored in a plurality of line buffers, followed by processing of the data in the line buffers to generate a rotated image.
The data processing components used in portable video devices generally present significant design constraints relating to processing capability and power management. In addition to these factors, data processing components used to process video signals present significant challenges with regard to memory management. Prior techniques discussed above for rotating a video image require large video storage buffers that occupy significant surface area on the data processing integrated circuits. It is apparent, therefore, that there is a need for an improved method and apparatus for processing video images that maximizes the use of memory resources, while decreasing the associated integrated circuit surface area devoted to video storage buffers.